draftkings no sweat bet returned less than my stake somehow.

Used one of those no sweat bonus bets for a late night baseball parlay - nothing fancy, just a regular 3-leg. Lost obviously, but when the site returned the stake as a bonus bet, it was actually lower than what I put in. I staked 25 but got a 20 bonus back. Don’t remember any rules saying it’d be docked for anything, or maybe I missed some fine print.

Not that I usually mess with these much since blackjack’s my thing, but kind of odd. Do these promos sometimes scale down the returns based on the odds or the sport? Or maybe I triggered some sneaky clause. Usually respect the variance and let it ride, but stuff like this makes me want to triple check every promo now. Anyone else run into something like this or am I just that lucky?